Apparatus for corrugating sets of fins on sectors of tubular elements



April 22, 1969 I E. E. TETART APPARATUS FOR CORRUGATING SETS 0F FINS ON SECTORS 0F TUBULAR ELEMENTS Sheet Filed Sept. 15, 1966 Fig. 1

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nv VEN fol? EMILE E. T'TAkT BY/6M/4KZW/ OW Y A ril 22, 1969 E. E. TETART 3,439,521

APPARATUS FOR CORRUGATING SETS OF FINS ON SECTORS OF TUBULAR ELEMENTS Filed Sept. 15, 1966 Sheet 2 of 2 J 1k; J AJK Ljk ,6 u a 5' 9 A ,18 ll 1 Fig.5

22a I 24c 24a 25a wvszvroe United States Patent 3,439,521 APPARATUS FOR CORRUGATING SETS 0F FINS 0N SECTORS 0F TUBULAR ELEMENTS Emile E. Tetart, Louvie-Juzon, France, assignor to Commissariat a IEnergie Atomique, Paris, France Filed Sept. 15, 1966, Ser. No. 579,669 Claims priority, application France, Sept. 17, 1965,

Int. Cl. B21d 31/0 0, 41/00; BZlj 7/16 US. Cl. 72-399 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to apparatus for corrugating set of fins.

In certain heat exchanger apparatus, use in made of tubular elements having sets of fins distributed over the surface thereof for increasing the heat-exchanging surface area. Some sheaths for fuel elements of nuclear reactors are constituted by such tubular elements comprising sets of fins which are corrugated further to improve the heat exchange and to minimize deformation of the fins during thermal cycles or during lamination.

It is an object of the present invention to provide apparatus which enables the machining of each set of fins by blades located coadjacently and which have punches of corrugated form which are engaged, by the action of cam, in the gaps separating the fins.

It is another object of the invention to ensure that the driving of each punch between the two fins causes the forming of the latter, two adjacent punches simultaneously shaping the fin disposed between them.

It is a further object of the invention to provide apparatus of multiple type, comprising as many series of blades as the tubular element has sets of fins, these blades being disposed around the said element. This forming of the fins may be carried out before the positioning of fuel element or after sheathing.

The present invention accordingly consists in apparatus for corrugating previously machined sets of fins on sectors of tubular elements, said apparatus comprising a series of blades relatively disposed to form a stack and each blade having one end in the form of a punch of tapered section and whose faces are corrugated, said punch being engageable in the space separating two fins to be corrugated under the action of a member acting on the end of the blades remote from said punch-form ends, and being displaced parallel to the axis of the series of blades.

In order that the invention may be more clearly understood, reference rwill now be made to the accompanying drawings which show certain embodiments thereof by way of example, and in which:

FIGURE 1 shows a view in longitudinal section of a set of fins during machining by means of apparatus according to the invention,

FIGURE 2 shows a view in perspective of the apparatus for corrugating the fins shown in FIG. 1,

FIGURE 3 shows a view in longitudinal section of another embodiment of apparatus according to the invention, and

FIGURE 4 shows an end view of a multiple machine for machining fins according to the invention.

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Referring now'to the drawings, in FIG. 1 there is shown a tubular element 1 which may be, in particular, a sheath for a nuclear reactor fuel element and which has external fins 2 previously machined. These fins 2 are separated by spaces 3 between which are progressively engaged the ends 4, in the fashion of a tapered punch, of blades 5 relatively located so as to form a stack whose axis corresponds to the axis of the fins. The progressive driving of the ends 4 in the form of a punch into the spaces 3 is achieved by a cam 6 (FIGS. 1 and 2) constituted by a plate having an inclined surface 7 which acts on rounded ends 8 of blades 5 remote from the ends 4 that form punches.

This cam 6 is driven parallel to .the axis of the set of blades 5 in the direction of the arrow A, by any convenient known means for example, a screw (not shown in the drawing) whose form and operation will be apparent to all skilled in the art of machines and mechanical devices generally.

Each end 4 of the blades 5 has its two major surfaces corrugated at 9, 9a, respectively, these surfaces being arranged so as to impart to the surfaces 10, 10a of two neighbouring fins 2, a corrugated form.

After each machining operation of one set of fins, the blades 5 are extracted and placed on another set of fins to commence another machining operation. These operations are repeated as many times as necessary to corrugate all of the fins of a sector.

The fins being mostly inclined with respect to the axis of a sector, a symmetrical tool is necessary to corrugate the fins of the symmetrical sector.

The embodiment of the apparatus shown in FIG. 3 is intended for machining a complete sector of fins in a single operation, the number of blades 11 being proportional .to the number of fins 2 of a sector. In thisv case, the blades 11 have openings 13 which constitute, when the blades are stacked, a channel in which is engaged a cam 14 constituted by a plate of which the central curved part 15 has a convex face 16 and a concave face 17. During its displacement in .the direction of the arrow A following an axial parallel to the axis of the blades 11, the cam 14 whose convex surface 16 rests against the edge 18 of the opening 13 and whose concave surface 15 against the edge 19, causes, in passing, the progressive thrust of the ends 12 acting as punches, into the spaces 3 between the fins, to a determined position of maximum penetration. Then, the blades 11 are retracted into the disengaged position, so that after the passage of the cam in the direction of the arrow A in the interior of the opening 13, the fins 2 are corrugated and the assembly of blades is entirely disengaged for a new machining of fins on another sector. It would also be possible to proceed with the corrugation of fins of different sectors of a sheath on a multiple machine as that shown in FIG 4.

The tubular element 20 which has different sectors provided with fins 21a, 21b, 21c is arranged in a support constituted by several sectors 22a, 22b, 220 which serve for the lateral guidance of several sets of blades 23a, 23b, 23c identical with blades 11 and which have, like the latter, openings 13 in which cams 24a and 24b, 240 are displaced.

It is suflicient to act simultaneously on the cams 24a, 24b, 240 by means of a jack to displace the latter and cause the inward thrust and the withdrawal of the blades 23a, 23b, 23c, which corrugate the fins 21a, 21b, 21c during the movement.

The latter arrangement is particularly advantageous due to the fact that the forces exerted on the tubular element 20 are distributed over its periphery and are 0 balanced.

It will be understood that the present invention is not limited to the embodiments described and illustrated but covers all modifications thereof within the scope of the appended claims.

What I claim is:

1. Apparatus for corrugating previously machined sets of parallel fins which are uniformly spaced apart on sectors of tubular elements, comprising: a series of similar blades relatively disposed to form a stack, each of the blades having one end portion in the form of a punch of tapered section and whose two major lateral faces are corrugated, the opposed corrugations of adjacent blades cooperating to define a corrugating passage therebetween, each of said blades having a surface spaced from the corrugating faces to be engaged and acted upon for inserting the punches in the spaces between adjacent fins, said stack, when disposed for corrugating fins on a sector, having its axis parallel to the axis of the fins to be corrugated, the punches of the stack being positioned with a punch in alignment with the space between each of the adjacent fins to be corrugated; and cam means movable parallel to the axis of the series of blades and from one end of the stack to the other end thereof and engageable with said surface of each blade in succession for progressively forcing the tapered corrugated sections of the blades radially inwardly into the spaces between adjacent fins thereby deforming and corrugating them.

2. Apparatus as claimed in claim 1, wherein said cam means acting on said blades is constituted by a cam plate that includes one inclined face which is successively brought into contact with the ends of said blades remote from the punch end.

3. Apparatus as claimed in claim 1, wherein said stack of blades is formed with an opening forming a passage extending parallel to the axis of the stack and from one end to the other end thereof, said cam means being disposed in said passage and being constituted by a plate having a central curved part that has a convex face and a concave face parallel thereto, said convex face being directed towards said punch-form ends of said blades.

4. Apparatus as claimed in claim 3 comprising a plurality of stacks of blades arranged about the periphery of a tubular element having a plurality of sectors bearing fins to be corrugated, support means for guiding the blades of each stack in a radial direction, and cam means acting simultaneously upon the blades of each stack for progressively forcing the corrugated sections of the blades of each stack radially inwardly between the respective fins for simultaneously corrugatiug the fins on all of the sectors.

References Cited UNITED STATES PATENTS 24,689 7/1859 Worthen et al. 72403 237,515 2/1881 Gould 72-400 1,623,916 4/1927 Frick 72403 2,357,605 9/ 1944 Nivison 72403 3,154,978 11/1964 Baker 72-402 CHARLES W. LANHAM, Primary Examiner.

E. SUTTON, Assistant Examiner.

US. Cl. X.R. 

